This invention relates to combustion turbine systems and prime movers for combustion turbine systems that can be used to power a blower that produces air for cooling an electrical generator and to selectively power a compressor of the combustion turbine system. This invention also relates to methods of using these prime movers and combustion turbine systems that employ them.
Combustion turbine systems generally include a compressor, a combustor and a turbine section. The compressor compresses air, and the air is directed to the combustor. In the combustor, the air is mixed with fuel, and this mixture is burned to produce a hot gas. The hot gas is sent through the turbine section of the combustion turbine system where a portion of the energy in the hot gas is converted into useful work. This work may include rotation of a rotor which drives a load, such as an electrical generator. After traveling through the turbine section, the hot gas is exhausted from the combustion turbine.
Typically, the compressor and the electrical generator are both mounted on the rotor that extends through the turbine section of the combustion turbine system.
Therefore, as the hot gas flows through the turbine section and causes the rotor to rotate, the compressor and the electrical generator are both driven by the rotation of the rotor. Thus, when the rotor shaft is driven in the turbine section by the expansion of the hot gas, electricity can be produced by the electrical generator.
Because electrical generators produce a significant amount of heat, they must be cooled. A heat exchanger may be disposed within the electrical generator in order to provide the requisite cooling. The heat exchanger may be employed in a cooling circuit that includes a blower for supplying air as the cooling medium to the heat exchanger and a cooler for cooling the air after it has been heated while traveling through the heat exchanger.
In prior art combustion turbine systems, the blower that provides cooling for the electrical generator may be mounted on a shaft of the electrical generator, so that rotation if the rotor shaft by the hot gas produced in the turbine section of the combustion turbine system will cause rotation of the blower. In other words, the combustion turbine acts as the prime mover for the blower.
In order to start a gas turbine, the compressor must be started so that is can provide the air at the requisite pressure for mixing with fuel to produce a hot gas to drive the rotor. As alluded to above, during normal operations of a combustion turbine system the compressor is powered by the hot gas that expands and drives the rotor in the turbine section. Since the mixture of fuel and compressed air needed to drive the turbine rotor and the compressor is not available upon starting the combustion turbine, a prime mover must be provided in order to start the compressor. Typically, the prime mover is an electrical induction motor. After the combustion turbine has been started and sufficient hot gas is produced, the compressor is powered by the rotation of the rotor and the prime mover that powers the compressor is no longer required.
In prior art combustion turbine systems, the prime mover for powering the blower motor for the cooling circuit of the electrical generator and the prime mover for starting the compressor were separate components. The prime mover for starting the compressor was used to merely start the compressor, and the prime mover for the blower was the combustion turbine.
This invention relates to improved combustion turbine systems that employ prime movers that can be used to selectively power a compressor upon starting a combustion turbine and be used to power a blower for producing a cooling medium for an electrical generator. This invention also relates to these prime movers themselves, and improved methods of using these combustion turbine systems employing the prime movers.